MONGOLIAN
FROST RINGS: Lamont dendrochronologist Gordon Jacoby collected this
sample of tree rings from a Siberian pine in Mongolia, which records the
years 534-539 C.E. (left to right). The narrow, distorted rings for 536
and 537 indicate a drastic cooling in the northern hemisphere that froze
sap in the cells during the growing season. Evidence for this abrupt climate
change points to a massive eruption of the volcanic precursor of Krakatoa.
Another theory invokes a cosmic impact that possibly triggered the eruption.
Magnification ~ 27.6 X